package initcmd

import (
    "os"
    "path/filepath"
    "strings"
    "testing"
)

func TestRun_GoProject(t *testing.T) {
    dir := t.TempDir()

    // Create a go.mod marker file.
    if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module example.com/test\n"), 0644); err != nil {
        t.Fatal(err)
    }
    // Create a source directory with a file.
    if err := os.Mkdir(filepath.Join(dir, "cmd"), 0755); err != nil {
        t.Fatal(err)
    }
    if err := os.WriteFile(filepath.Join(dir, "cmd", "main.go"), []byte("package main\n"), 0644); err != nil {
        t.Fatal(err)
    }

    if err := Run(dir, Options{}); err != nil {
        t.Fatalf("Run() returned error: %v", err)
    }

    data, err := os.ReadFile(filepath.Join(dir, "AGENT.md"))
    if err != nil {
        t.Fatalf("reading AGENT.md: %v", err)
    }

    content := string(data)

    // Check project type detection.
    if !strings.Contains(content, "Go") {
        t.Error("expected AGENT.md to contain 'Go' project type")
    }

    // Check directory listing includes go.mod.
    if !strings.Contains(content, "go.mod") {
        t.Error("expected AGENT.md to list go.mod")
    }

    // Check directory listing includes cmd/ subdirectory.
    if !strings.Contains(content, "cmd/") {
        t.Error("expected AGENT.md to list cmd/ directory")
    }

    // Check that main.go appears under cmd/.
    if !strings.Contains(content, "main.go") {
        t.Error("expected AGENT.md to list main.go inside cmd/")
    }

    // Check placeholder sections exist.
    for _, section := range []string{"## Build Commands", "## Architecture", "## Key Files", "## Notes"} {
        if !strings.Contains(content, section) {
            t.Errorf("expected AGENT.md to contain section %q", section)
        }
    }
}

func TestRun_EmptyDirectory(t *testing.T) {
    dir := t.TempDir()

    if err := Run(dir, Options{}); err != nil {
        t.Fatalf("Run() returned error: %v", err)
    }

    data, err := os.ReadFile(filepath.Join(dir, "AGENT.md"))
    if err != nil {
        t.Fatalf("reading AGENT.md: %v", err)
    }

    content := string(data)

    // With no marker files, project type should be "Unknown".
    if !strings.Contains(content, "Unknown") {
        t.Error("expected AGENT.md to contain 'Unknown' project type for empty dir")
    }
}

func TestRun_ExistingAgentMD_NoOverwrite(t *testing.T) {
    dir := t.TempDir()

    agentPath := filepath.Join(dir, "AGENT.md")
    original := "# Original content\n"
    if err := os.WriteFile(agentPath, []byte(original), 0644); err != nil {
        t.Fatal(err)
    }

    err := Run(dir, Options{})
    if err == nil {
        t.Fatal("expected error when AGENT.md already exists")
    }

    if !strings.Contains(err.Error(), "already exists") {
        t.Errorf("expected 'already exists' in error, got: %v", err)
    }

    // Verify file was not modified.
    data, err := os.ReadFile(agentPath)
    if err != nil {
        t.Fatal(err)
    }
    if string(data) != original {
        t.Error("AGENT.md was unexpectedly modified")
    }
}

func TestRun_Force(t *testing.T) {
    dir := t.TempDir()

    agentPath := filepath.Join(dir, "AGENT.md")
    if err := os.WriteFile(agentPath, []byte("# Old content\n"), 0644); err != nil {
        t.Fatal(err)
    }

    // Create a go.mod so the new content is distinguishable.
    if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module test\n"), 0644); err != nil {
        t.Fatal(err)
    }

    if err := Run(dir, Options{Force: true}); err != nil {
        t.Fatalf("Run() with Force=true returned error: %v", err)
    }

    data, err := os.ReadFile(agentPath)
    if err != nil {
        t.Fatal(err)
    }

    content := string(data)
    if strings.Contains(content, "Old content") {
        t.Error("AGENT.md should have been overwritten with Force=true")
    }
    if !strings.Contains(content, "Go") {
        t.Error("expected new AGENT.md to detect Go project type")
    }
}